According to prior art champignon mushrooms are grown on a substrate consisting for example of compost treated in a suitable manner and supplemented with mycocelial filaments. The filaments are grown in suitable temperature and humidity, and it is supplied with additional nutrients, and the substrate is covered with a layer of peat, if necessary. Champignon mushrooms do not need light in order to grow. Champignon mushrooms that have grown sufficiently are picked and several harvests are obtained from the substrate. The growing methods are well known, and the picking is typically performed manually.
The substrate is typically placed on shelves, in which there are several superimposed layers, wherein the floor space is efficiently utilized. The shelves are typically dimensioned in such a manner that manual picking from the entire substrate is possible, wherein the shelves are long and narrow. The shelves form for example different kinds of boxes, in which the substrate is placed. The substrate is often uneven or it has a curved shape.
In prior art apparatuses have been developed for picking of mushrooms, which automatically detect the mushrooms, pick them up, cut the stem and transfer the mushroom either on a conveyor or in a collection vessel. One apparatus is disclosed in the document WO 91/11902, in which the apparatus comprises cameras and suction pads by means of which the mushrooms are transferred into containers. However, the transfer mechanism of the suction pads is complex, heavy and it occupies a great deal of space. It is necessary to arrange several cameras in the apparatus so that it would be possible to image the entire width of the substrate. When only one camera is used, the image thus formed is very distorted at its edge areas, wherein significant imprecision occurs in the determining the location of the mushroom, as the height of the mushrooms also varies. Because the substrate is typically positioned on low shelves, the camera must be positioned very low as well, which, in turn, reduces the area that can be scanned with the camera. The addition of cameras increases the costs and the size of the device.
One apparatus is disclosed in the document WO 93/00793, in which the apparatus comprises several cameras and a suction pad attached at the end of a moving arm, by means of which the mushrooms are picked up and dropped on a moving belt. The purpose of the cameras is to scan the substrate and determine the location of a mushroom. The drawback of said apparatus is, however, that it does not recognize the height at which the mushroom is located. In practice, the height or position of the mushroom in the vertical direction varies significantly. The apparatus lowers the moving arm always at the same height and the flexible structure of the suction pad grips the mushroom. As for the suction pad, it is not certain that the suction pad will grip a mushroom located at a distance and that this will take place sufficiently gently. The positioning of the suction pad accurately at the location of the mushroom also requires the movement of the carriage, wherein picking becomes slower.
Other apparatuses for picking of mushrooms have been disclosed in documents EP 0428284 and NL 6814542.
Document U.S. Pat. No. 4,425,751 discloses a picking apparatus and a camera by means of which it is possible to detect an asparagus for picking purposes. Document U.S. Pat. No. 4,843,561 discloses an apparatus by means of which fruit or vegetables can be picked by means of a camera.